The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs. Each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs.
In recent decades, the chemical mechanical polishing (CMP) process has been used to planarize layers to build up ICs, thereby helping to provide more precisely structured device features on the ICs. The CMP process is a planarization process that combines chemical removal with mechanical polishing. The CMP polishes and removes materials from the wafer, and works on multi-material surfaces.
However, these advances have increased the complexity of processing and manufacturing ICs. Since feature sizes continue to decrease, fabrication processes including the CMP processes continue to become more difficult to perform. Therefore, it is a challenge to form reliable semiconductor devices at smaller and smaller sizes.